The translation of xenogenic eukaryotic mRNA's has been previously studied in the frog oocyte as well as in a variety of cell free systems. We have sequestrated mRNA within large unilamellar ether infusion liposomes. These liposomes are able to fuse with cells in culture and insert the entrapped message without degradation by nucleases. We have employed this procedure to insert rabbit globin mRNA into a human cell line and have been able to demonstrate the production of rabbit globin by physicochemical and immunologic techniques. If this procedure is to be expanded to include messages which are only available in small quantities, the efficiency of liposome-mediated transfer of mRNA must be maximized. We have made a thorough study of the effect of the alteration of numerous paramiters involved with the liposome-cell interaction, and have been able to achieve as high as 20 percent cellular incorporation of liposome-sequestered 3H-RNA. We feel this will enable us to efficiently study the regulation of protein synthesis in a differentiated cellular environment. If liposomes are to be used with lymphocytes it is essential to assess the effect of the liposomes themselves on the function of these cells. We have started to investigate this question by studying the effect of liposomes on the expression of surface immunoglobulins. We have found that liposomes without cholesterol causes a loss of lymphocyte surface Ig after cocultivation for 1 hr at 37 degrees. This loss has been shown to be the result of a capping phenomenon which can be modulated by regulation of the rate of cholesterol biosynthesis. Further investigation of this effect is presently underway.